Spark plug



March24, 1931. BIDWELL 1,797,817

SPARK PLUG Filed July 29, 1927 EZILZIIIIIIII:

EARL ELBwwELL A TTORNEY.

INVENTOR.

Patented Mar. 24, 1931 UNITE D STATES [PATENT OFFICE EARL E. BID'WELL, orwIcnrrA, mm

application and m 29, 1927. Serial no. 209,302;

This invention relates to spark plugs for internal combustion engines and among the objectsthereof may be mentioned the provision of means for providing a spark plug with an ignition chamber within the shell of such form that when the fuel is initially combusted in'the spark plug chamber, it,will discharge "into the combustion chamber ofthe motor with suflicient force to create a turbulence of the fuel in the combustion chamber of the motor at the time of ignition and by increasing the rate of combustion of the fuel in the combustion chamber (that is, cutting down the lag of combustion) a marked increase in. the pick-up of the motor and in the general power efliciency thereof will be assured. Because of the more perfect combustion, higher speed can be obtained, while at the same time the fuel consumption is less.'

The consumption chamber in the spark plug shell is of such form that it rids itself of carbon, oil and the like at each explosion,

and due to a Venturi action at the restricted discharge orifice, the burning gases from the chamberwithin the plug not only ignitethe gases in the combustion chamber of the enine but they also cause ap reciable tur-.

ulence. The temperature o the positive electrode and the insulator therefor is constantly high enough to vaporize the oil so that it is consumed as fuel. Any oil which enters the combustion chamber will contact with the hot end of the electrode whicha'cts as a bafile and causes the oil to heat to the va orizing temperature. -So much so I have ound in actual practice that it has become necessary to retard the s' ark on account of the rapid combustion which takes place in the combustion chamber of the en e. t 9 I have found that it is quite important to have the electrode ofi-set with respect to the outlet orifice of the combustion chamber because the outlet orifice also serves as an inlet orificefor the fresh gas and in the event that oil enters the chamber, it will not wet the elec trodes or porcelain because it will never get past the baflle on the end of the electrode,

' which 'would happen if the electrodes were in line with the orifice. I have, also, found it to be advantageous to set the negativeelecdrawings in which:

trode, (that is, the one attached to the shell) in line with the positive electrode; as for example in the case of'plugs used in racingautomobile and airplane engines, because when the'e'ngine speeds up, the positive electrode will expand, automatically shortening the gap between the two electrodes which is desirable under certain conditions. I have, also, provided means formaintaining the insulating porcelain and therefore, the positive electrode in proper spaced relation withthe shell. Other objects and advantages of the invention will be referred to hereinafter, reference being had to the accompanying ,6

' Fig. 1 is an elevation of the spark plug, partly in section.

Fig. 2 is an end view taken on line 2 2 in Fig. 1 and Fig. 3 is a showlng a different position of thenegative electrode to forma spark gap.

' The shell 1 is shown as provided with the usual externally threadedjend 2 whereby the plug can be screwed into the engine block. The opposite end of the shell has an internally,threaded socket to receive a packing 'gland 3 which carries the insulation 4. The

end of which receives a j am nut 8, which cooperates with the binding nut 7 to hold the end of the feed wire. Under the jam nut 8 is a washer ,8 to prevent leakage at the outer end of the porcelain. The electrode 6 is provided at its inner end with a cup-shaped head or disc 9 which is drawn ,tightlyagainst the insulator by screwing up the nut 8; The head 9 constitutes the-effective inner end of the'insulator 6 for co-operation with the negative electrode to be referred to hereinafter.

B and C are two annular shoulders in spaced relation within the shell. Two copperwashers 10 and 10 abut against the shou ders and hold the insulator or porcelain in proper spaced relation inside the shell. These washers flex when the. porcelainexpands or contracts. 11 is the restricted inlet and outlet longitudinal sectional view, 70 I orifice for the chamber 5 and at its outer end it 1s slightly flared, as at 12, to provide a dispersive effect for the combusted gases as they are forced out through the orifice due chamber of'the engine and to causeimmediate ignition of all of the gases in the comon the compression stroke a clean charge will be introduced into combustion chamber 5 bustion chamber instead of permitting the usual lag of ignition incident to the use of the ordinary spark plug where the spark initially ignites the gases within the combustion chamber at a point. The negative electrode 13 is elf-set out of axial alinement with the orifice 11 and terminates in spaced relation with the edge 14 of the head 9 which is relatively sharp comparedwith the diameter of electrode 13, the head 9 having sufiicient material to prevent its becoming hot enough to cause pre-ignition independent of the spark. Since the negative electrode 13 carried by the shell-is spaced axially of the plug from edge 14, and since the electrode 13 is carried by the cooled wall of the engine block, the expansion of the porcelain A and electrode 9 will cause the spark gap to be decreased as the motor heats up. As a re sult when the engine is running at high s eed, there will be a shorter gap between the ead 9 and the electrode 13 and at low speed this gap will be slightly increased due to dropping of temperature in the engine. It will also be observed that the annular head of th positive electrode, by loosening packing gland 3 and revolving the porcelain with electrode 3, 9, 14 can be turned from time to time to present new contact points to the positive electrode. V I

On the intake stroke of the piston a slight vacuum will be created in chamber 5 so that ready to fine when the piston reaches the top of the compression stroke and the. timer causes the spark to jump across thega'p between the electrodes in the shell. Then, during the down stroke of the piston, the burnt gases will be violently introduced into the combustible gases in the cylinder as previously explained. In Fig. 3 the electrode 13 is, introduced through the side of the shell, but

its effective end is in line with the head 9 in substantially the same manner as the electrode 13 shown in Fig. 1.

It will be noted' that the bottom of the chamber?) has symmetrically formed wall surface to bend the gases in easy stream lines so that no carbon can :form on shoulders or ledges inside the chamber on account of the velocity of the gases escaping from this cham ber wiping these smooth walls free from all foreign matter.

The proportional size and the shape of chamber 5 is important and is the result of many experiments. The space about the insulator 4, in the chamber must not be too great and the electrode 14 must be located well below the top of the chamber. The space shown between the electrode 14 and the orifice 11 is about the maximum permissible.

Minor changes may be made in the physical I embodiment of the invention and in the portion of parts within the scope of the appended claims without departing from the spirit of the invention.

What I claim and desire to secure by Letters-Patent is:

1. A spark plug comprising a shell having a chamber with a restricted, unobstructed,

opening through which fresh fuel may pass into the chamber and burning gases may pass from the chamber, the wall of the chamber about the opening curving toward the opning, an electrode extending into the chamber, an insulator between the shell and the electrode, a second electrode in the chamber above said orifice and forming a spark gap with said first named electrode said gap ofi'set with respect to said opening.

2. A spark plug comprising a shell having a combustion chamber therein with an inlet and outlet orifice, an electrode and insulator cooperating with the shell and extending into said chamber in line with said orifice, and an electrode carried by said shell and extending into said chamber and having a gap laterally offset from said orifice and spaced from said first-named electrode in a direction lengthwise of the axis of the plug.

3. Aspark plug comprising a shell having an electrode insulated therefrom and comprising a part which is ofi center with respect to said shell, said shell containing a combustion chamber having a single inlet and outlet orifice in line with said.electrode, the inner end of said electrode being of greater diameter than the diameter of said orifice, and an electrode in said chamber spaced from said part of said first-named electrode in a" direction lengthwise of the axis of the plug, whereby the gap between the two electrodes will be varied by the expansion andcontraction of said first-namd electrode.

4. In a spark plug a shell containing a chamber axially positioned therein, an aperture in said shell. in vertical alignment with up w a chamber provided with a restricted, unobstructed, aperture, a dished electrode in said chamber, and asecond electrode cooperating with the annular rim of the dished said dished electrode.

6. A spark plug comprising a shell, an electrode, an insulator between said shell and said elect-rode, said shell containing a chamber and said electrode extending into'said chamber, said chamber having a restricted, unobstructed opening, with the wall of said chamber converging toward said opening and through which opening the fresh fuel may pass into said chamber and burning ases pass therefrom, and an electrode in sai chamber complementary to said first-named electrode and forming therewith a spark gap ofiset laterally with respect to said opening in said chamber and spaced from said first-named electrode in a direction lengthwise of the axis of the plug.

In testimony whereof I aifix my signature.

EARL E. BIDWELL.

portion of I 

